The high temperature chemistry of the N-O-H-C system has been studied to determine the production of NO and CO by a atmospheric lightning. The yield of NO is found to be equivalent to results obtained for a pure N2/O2 atmosphere. The CO yield is highly dependent upon the detailed cooling processes within the discharge and thus an experiment designed to measure the CO source in discharges could yield useful insights into the discharge itself. An upper limit of 3.5¿1011 g CO yr-1 is estimated for the global CO source from lightning.